Table 1.
Characteristics of the patients with stage IV lung cancer harboring uncommon mutation.
| All Stage IV Patients | Patients Receiving First-Line TKI | |
|---|---|---|
| n | 62 | 57 |
| Age (year), mean ± SD | 65 ± 12 | 66 ± 12 |
| Age (year), median (IQR) | 64 (56–74) | 65 (56–75) |
| Sex, n (%) | ||
| Female | 36 (58%) | 32 (56%) |
| Male | 26 (42%) | 25 (44%) |
| Smoking history, n (%) | ||
| Never | 44 (71%) | 40 (70%) |
| Current | 18 (29%) | 17 (30%) |
| Performance status, n (%) | ||
| ECOG 0–1 | 44 (71%) | 39 (68%) |
| ECOG 2–4 | 18 (29%) | 18 (32%) |
| TKI medication, n (%) | ||
| Afatinib | 19 (31%) | 17 (30%) |
| Gefitinib | 32 (52%) | 31 (54%) |
| Erlotinib | 11 (18%) | 9 (16%) |
| TKI use, n (%) | ||
| 1st-line treatment | 57 (92%) | 57 (100%) |
| 2nd-line treatment | 3 (5%) | |
| after 2nd-line treatment | 2 (3%) | |
| Number of metastatic sites, n (%) | ||
| =1 | 29 (47%) | 27 (47%) |
| ≥2 | 33 (53%) | 30 (53%) |
| Metastatic site, n (%) | ||
| Brain | 16 (26%) | 14 (25%) |
| Leptomeningeal | 2 (3%) | 2 (4%) |
| Lung | 23 (37%) | 20 (35%) |
| Bone | 32 (52%) | 30 (53%) |
| Pleural | 29 (47%) | 29 (51%) |
| Pericardial | 5 (8%) | 5 (9%) |
| Liver | 10 (16%) | 9 (16%) |
| Adrenal | 5 (8%) | 5 (9%) |
| Renal | 1 (2%) | 0 (0%) |
| Mutation site, n (%) | ||
| Exon 18 G719X | 14 (23%) | 14 (25%) |
| Exon 18 other mutation | 2 (3%) | 2 (4%) |
| Exon 18 G719X + exon 18 other mutation | 5 (8%) | 5 (9%) |
| Exon 20 insertion | 16 (26%) | 13 (23%) |
| Exon 20 point mutation | 3 (5%) | 3 (5%) |
| Exon 21 L861Q | 13 (21%) | 13 (23%) |
| Exon 18 G719X + exon 20 S768I | 3 (5%) | 3 (5%) |
| Exon 18 G719X + exon 21 L861Q | 2 (3%) | 2 (4%) |
| Exon 21 L858R + exon 20 S768I | 3 (5%) | 2 (4%) |
| Exon 21 L858R + exon 20 Q812* | 1 (2%) | 0 (0%) |
| Mutation site classified by exon, n (%) | ||
| Mutation only in exon 18 | 21 (34%) | 21 (37%) |
| Mutation only in exon 20 | 19 (31%) | 16 (28%) |
| Mutation only in exon 21 | 13 (21%) | 13 (23%) |
| Mutations in multiple exons | 9 (15%) | 7 (12%) |
| Mutation site classified by susceptibility †, n (%) | ||
| Single sensitizing uncommon mutation | 27 (44%) | 27 (47%) |
| Multiple sensitizing mutations | 8 (13%) | 7 (12%) |
| A sensitizing mutation and a resistant uncommon mutation | 6 (10%) | 5 (9%) |
| Other resistant uncommon mutations | 21 (34%) | 18 (32%) |
| Initial response to TKI, n (%) | ||
| Partial response | 21 (34%) | 19 (33%) |
| Stable disease | 24 (39%) | 22 (39%) |
| Progressive disease | 17 (27%) | 16 (28%) |
| Response rate to TKI | 21 (34%) | 19 (33%) |
| Disease control rate to TKI | 45 (73%) | 41 (72%) |
| Median follow-up time (months) | 13.0 | 11.5 |
| Median PFS on TKI (months) | 7.5 | 7.4 |
| Median OS (month) | 17.0 | 16.1 |
Abbreviations: ECOG = Eastern Cooperative Oncology Group; TTF-1 = thyroid transcription factor 1. † Mutation site classified by susceptibility: “Single sensitizing uncommon mutation” included exon18 G719X and exon21 L861Q; “multiple sensitizing mutations” included exon18 G719X + exon20 S768I, exon18 G719X + exon21 L861Q, and exon21 L858R + exon20 S768I; “a sensitizing mutation and a resistant uncommon mutation” included exon18 G719X + exon18 other and exon21 L858R + exon20 Q812*; “other resistant uncommon mutations” included exon 18 other mutation, exon 20 insertion, and exon 20 point mutation.